Research on instability mechanism and control technology of high-stress red shale roadway

In order to solve the maintenance problem of high-stress red shale roadway, the No.2 mine of Ping’an phosphate mine is taken as the engineering background.Theoretical analysis, numerical simulation, experimental test and engineering practice are used to study the microstructure characteristics of red shale and the mechanism of roadway instability.The results show that the pore diameter of red shale is mainly distributed in 0-50 nm and 10-200 μm.In the natural state, the micropore in 10-200 μm accounts for 37.45% of the total pore volume, and it will increase to 45.82% after water absorption.The weakening of rock strength caused by water absorption is an important reason for the instability and failure of red shale roadway.The roadway supporting measures including high-strength bolt-grouting, grid arch and small diameter anchor cable are proposed.The supporting structure can adapt to the initial deformation requirements of the red shale roadway, effectively limit the excessive deformation of the roadway, and fully mobilize the bearing capacity of deep surrounding rocks.Field monitoring show that the maximum deformation of the two ribs of the red shale roadway is within 100 mm, the roof subsidence is controlled within 40 mm, and the force of the anchor cable is 100-120 kN and tends to be stable, indicating that the new scheme has good control effect.